Fuel pump



Feb '7', 1939. w. H. LAFFERTY FUEL PUMP Filed May 14, 1936 2 Sheets-$112M 1 Patented Feb. 7, 1939 PATENT OFFICE I FUEL PUMP William H. rairorty, Toledo, Ohio Application May 14, 1936, Serial No; 79,662 3 Claims. (01. 103-152) This invention relates to apparatus for pumping fluids, but more particularly for pumping or forcing liquids, such as gasoline, from the supply tank or reservoir to the engine carburetor. More particularly, it relates to suction controlled apparatus for pumping liquids wherein a pumping element is rapidly reciprocated under the influence of suction impulses, and operates to impart a driving force on the liquid or other fiuidwhich is being acted upon.

In its preferred form, the invention comprises a flexible pumping element which cooperates with a driving or actuating element to provide a substantially airtight chamber, these two elements of materially diiferent areas. Atmospheric air is introduced between these elements to create an effective driving force against the larger element to cooperate and assist the suction or sub-atmospheric pressure created on the outer side of the larger element. This operation takes place periodically or recurrently and is effective in imparting'an abrupt or snap reciprocation to the pumping element. For example, the suction from the intake manifold of the engine may be utilized and the force of this suction is considerably increased by employing atmospheric pressure so that instead of a sluggish, tardy reciprocation to the parts, a more abrupt action isobtained.

An object is to produce a simple and efflcient apparatus or mechanism for accomplishing the above purpose, particularly to utilize the suction of the intake manifold for actuating the pump so that rapid reciprocation is secured and adequate pumping power generated to insure a sumcient volume of liquid is delivered to the carburetor under all conditions of service.

Another object is to produce a fluid pump which is simple in construction eilicient in operation and which embodies the novel features of construction and method of operation hereinafter set forth.

By way of illustration embodiments of the invention are shown in the attached drawings, in which- Figure. 1 is a vertical sectional elevation of a fuel pump embodying the invention;

Figure 2 is a vertical sectional elevation on the line 2-2 of Figure 1 showing a valve detail;

Figure 3 is an enlarged sectional view showing the valve actuating mechanism;

-Figure 4 is a vertical sectional view on the line 4-4 of Figure 1;

liquids such as gasoline. the washer i2 is relatively large and its inside diameter of the pumping chamber 28.

Figure 5 is a transverse sectional view on the line 5-5 of Figure 1;

Figure 6 is a vertical elevation partly in section of an alternate form of pump embodying three diaphragms instead of two; 5

Figure 7 is a vertical sectional elevation on the line 1-1 of Figure 6; and

Figure 8 is a vertical sectional elevation of another form of pump in which a spring is utilized for driving the diaphragm members in one 10 direction. p

In the form of the invention shown in Figures 1 to 5 the fuel pump comprises a housing having a lower section ill and upper section I 1 between whch are disposed packing washers ,i2 and i2 the parts being secured together by screw l3. The upper end of the section II is closed by a screw cap M. The parts are fitted together to provide substantially an air-tight chamber l5. Forming a part of thelower section I0 is a bracket arm i6 which is secured by screws I! to any suitable mounting.

Leading to the housing section I0 is an inlet duct I8 which may extend from a gasoline tank of an automobile. The duct l8 terminates in the upper extending passage l9 leading to the chamber l5 and controlling the passage I8 is a valve 20 which is urged by a spring 2| to its seat. From the chamber IS the fuel is forced downwardly through a vertically disposed passage 22 which joins with a lateral passage 23 controlled by an outlet valve 24 urged to its seat by a coil spring 25. The passage 23 constitutes the outlet passage and leads to the engine carburetor.

The chamber I5 is divided into a fuel pumping chamber 26 and a suction chamber 21 by a flexible diaphragm arrangement as will hereinafter he described. It will be noted that .the diameter of the fuel pumping chamber 26 in the 40 region of the diaphragms is considerably less than that of the suction chamber directly above the diaphragm arrangement.

Clamped between the washer l2 and the housing section I!) is a flexible diaphragm 28 of any suitable material which is unaffected by It will be noted that diameter is substantially the same as the inside nected centrally to the diaphragm 28 is a post 29 which extends through an opening in a dia.

phragm and is clamped thereto by an outer disc 30 and a spacer member 3|.

Disposed above the diaphragm 28 is another diaphragm 32 which is clamped between the upper portion of the washer |2 and the housing section II, the washer I2 having a much larger internal diameter than the washer l2, thereby 5 exposing a much larger area of the diaphragm 32 than is exposed by the diaphragm 28. The

diaphragm 32 is apertured to receive the post 29 and a disc 33 cooperates with the spacer 3| in clamping the diaphragm in position, a nut 34 1 on a screw threaded portion of the post holding these parts together.

The upper end of the post 29 is connected by a coil spring 35 to the housing section II and opposed to the spring 35 is a somewhat weaker spring 36 which is connected at one end to-the post 29 and at' the opposite end to the outer end of an arm 31. The arm 31.is secured eccentrically to an oscillatory valve 38 which is mounted at substantially right angles to the post 29 withgo in a valve chest 39 forming a part of the housing section II. Leading from the valve chest 39 is a duct 49 which extends to the source of fiction, such as the intake manifold of the enu Extending vertically through the valve chest 39 is a passage 4|, the outer end of which is open to the atmosphere and the inner end of which opens to the suction chamber 21. Adjacent the passage 4| is a passage 42, the outer end of which opens to the duct 48, the inner end thereof opening to the suction chamber 21. Also opening to the duct 40 is a passage 43, the inner end of which opens to a lateral passage 44 formed in the washers I2 and I2, the passage 44 opening into the space he- .5 tween the diaphragms 28 and 32. Also extending through the valve chest is a passage 45, the

outer end of which is open to the atmosphere and the inner end of which also opens into the passage 44.

The valve 38 is provided with a plurality of ports which periodically register with passages 4| and 43, or with passages 43 and 45. As shown, the port 46 is adapted alternately to open and close the passage 4|, and at the same time the valve is in such position that when the port 46 is in alignment with the passage 4| a valve port 41 is in alignment with the passage 43. Thus air is sucked or drawn out of the space between the diaphragms 28 and 32 and at the same time the suction chamber 21 is open to the atmosphere through the passage 4| and port 46.

When the valve 38 is moved through a substantially 90 arc, the suction passage 42 is opened by a valve port 48 being brought into registration 55 therewith, and at the same time a valve port 49 is brought into registry with the atmospheric pas- ,sage 48. When one pair of passages in the valve chest 38 are opened, the other pair are closed. as will be apparent. It will be noted that the so outer end of the valve is provided with a head 50 against which a coil spring 5| bears, a screw threaded cap 52 providing an abutment for the opposite end of the springs In operation, assuming that parts are in posi- 05 tion shown in Figure 1, air is withdrawn from the suction chamber 21 through the passage 42 and valve port 48. At the same time atmospheric air is admitted to the space between the diaphragms 28 and 32 through the passage and valve port 70 48. It will be apparent that a relatively large area on the upper side of the diaphragm 32 is exposed to the suction or vacuum created through the intake manifold duct 48. Attention is called to the relative areas of the underside of the flexible diaphragm 32 and the exposed upper portion of the lower diaphragm 28. It will appear that there is considerably larger area of the upper diaphragm 32 exposed than there is of the lower diaphragm 28. Consequently, the atmospheric pressure acting downwardly on the lower diaphragm 28 and the atmospheric pressure acting upwardly on an equal area of the upper diaphragm 32 equalize each other. However, inasmuch as there is greater area on the upper diaphragm 32 exposed to atmospheric pressure, the action of the suction from the duct 40 tending to draw the diaphragm 32 upwardly will be assisted by the effective atmospheric pressure against the underside thereof. Obviously the normal pull on the underside of the diaphragm 32 in pounds per square inch will be increased by the square inch surface increase in the larger diaphragm 32 over the smaller diaphragm 28. Thus atmospheric pressure assists the suction and makes for a more rapid or more abrupt movement of the diaphragms, a feature of considerable importance where the apparatus is used in an automobile for pumping gasoline from the supply tank to the carburetor.

It will thus be apparent that the diaphragms 28 and 32 will be moved upwardly and such movement will continue until the post 29 has moved suificiently so that the spring 38 exerts a pull against the arm 31 to quickly move or oscillate the valve 38 to its other position at which time the valve ports 46 and 41 are brought into registration respectively with the valve chest passages 4| and 43. As shown in Figure 2, the head of the valve 38 is provided with stop surfaces which abut against a pin 53 carried by the valve chest 39. When the valve is moved to this latter position. it will be apparent that the suction chamber 21 is open to atmosphere through the passage 4| and suction is created in the space between the diaphragms 28 and 32. The sub-atmospheric pressure created therein will equalize itself with respect to the exposed portion of the diaphragm 28 and asimilar area on the diaphragm 32, leaving an effective vacuum or pull with respect to the diaphragm 32 of an area equal to the difference between the exposed areas of the two diaphragms. This pull coupled with the atmospheric pressure against the upper side of the diaphragm 32, air being admitted through the valve chest passage 4| and valve port 46, will abruptly move the diaphragms downwardly, whereupon the above described operation will be repeated.

, It will be apparent that when the diaphragm 28 flexes upwardly a suction will be created in the pumping chamber 26 drawing in fuel through the passage l8, past the valve 20 and into the pumping chamber through the vertical passage l9. When the diaphragm 28 is moved downwardly, the fluid in the pumping chamber 26 will be forced therefrom through the vertical passage 22 into the passage 23, unseating the valve 24 and thus to the engine carburetor.

If there is suiflcient gasoline in the carburetor it is undesirable that more fuel be forced to it and for that purpose a vertical passage 54 leads from the intake passage l8 to the pumping chamber 28 in advance of the passage IS. The passage 54 is controlled by a spring pressed valve 55, the spring being of a predetermined force which will unseat only when the pressure in the discharge line exceeds a predetermined maximum. At that time it will be seen that liquid will be drawn into the pumping chamber 26 through the passage I9 and upon the suction stroke of the diaphragm 28 and discharged therefrom through the passage 66 without forcing any fuel from the apparatus.

In the form shown in Figures 6 and 7 the valve and means for actuating it are the same as above described. In this form the diaphragms 28" and 32 are also the same as above described, having similar exposed diiferential areas. In this form an additional diaphragm 56 is disposed below the diaphragm 28 in the restricted portion 1 of the pumping chamber. Carried by the diaphragm 56 is a cup 51 into which a plunger 58 of the diaphragm-actuated post 1'9 extends. On

the lower end of the extension 58 is a head 59 which abuts against one end of a coil spring 60, the opposite end seating in the bottom of the cup. Fuel is drawn in through the inlet passage l8 past the'spring pressed valve Z0 into the pumping chamber 26 and is discharged therefrom, unseating the spring pressed discharge valve 24 into the outlet passage 23* leading to the carburetor. The diaphragm 56 flexes in accordance with the flexing of the diaphragm 26* as above described, but in the event that sufllcient gasoline has been delivered to the carburetor and a back pressure is built up in the discharge line 23, the post 29 will compress the spring 60 (as shown) without imparting any efiective movement to the diaphragm 56. It will be understood that the strength of the spring 60 is so 30- chosen that normally it will not yield but only when the pressure in the discharge line exceeds a predetermined maximum pressure. The diaphragms 2B and 32 are shown flexed downwardly and the spring 60 somewhat compressed, the diaphragm 56 being unflexed.

The action of the pump shown in Figure 8 is similar to that above described except that a coil 'spring 6| actuates the diaphragm structure in one direction, a combination of suction and atmospheric pressure operating to actuate the diaphragms in the opposite direction. As shown, a

spring 6| surrounds the post 29", hearing at one end against the housing section II and at the opposite end against a frustoconical plate memher 62. A diaphragm 32 is clamped to the outer edge of the plate 62 at its inner edge and at its outer edge is clamped between the housing sections II and II. The walls of the housing section ll directly beneath the diaphragm 32 incline downwardly and inwardly substantially as shown and a second diaphragm 28 is clamped at its outer edge to the housing section II and at its inner edge to the plate 62 .by a plate 63.

In this form the oscillatory valve 38 has two ports 64 and 65 at right angles to each other which register respectively with valve chest passages 66 and 61. When suction from the intake manifold through the duct 40 is created against the upper side of the frustoconical plate 62 and m diaphragm 32 at thesame time atmospheric air entering through a port 68 in the housing section 'Il ,'between the diaphragms 32 and 28 exerts an eilective pressure upwardly as will readily appear, since the exposed area of the g5 diaphragm 28 is less than half of the exposed 75 through an inlet 69, past a spring seated valve III and into the pumping chamber beneath the plate 63 and diaphragm 28 On the down stroke of the pump the fuel is forced past a spring seated valve ll into a discharge line 12. The strength of the coil spring 6i is so chosen that when the pressure in the discharge line 12 exceeds a predetermined maximum, the force of the spring 6| will be insuflicient to return the parts to normal position.

It is to be understood that numerous changes in detail of construction, arrangement and operation may be effected without departing from the spirit of the invention, especially as defined in the appended claims- What I claim is:

1. In a fluid pump having a pump housing, a

flexible pumping diaphragm-and a'flexible actuating diaphragm of unequal eil'ective areas within said housing, means attaching said diaphragms to said housing providing a pumping chamber, anair-tight chamber between said diaphragms and a pressure chamber above the larger diaphragm, said pump comprising means providing suction and vent passages respectively to each side of the actuating diaphragm, an operative connection between said diaphragms, a pot. projecting from the outer side of said actuating diaphragm, and a valve actuated by-said post and operative to control said passages for recurrently connecting opposite sides of said actuating diaphragm to the suction and vent passages respectively, the actuating diaphragm having the larger effective area so that the forces of atmospheric and subatmospheric pressure exerted thereagainst overcome such forces imposed on the pumping diaphragm whereby both diaphragmsare driven in one direction and then in the opposite direction.

2. In a fluid pump having a flexible pumping diaphragm and a flexible actuating diaphragm of unequal effective areas within said housing, means attaching said diaphragms to said housing providinga pumping chamber, an air-tight chamber between said diaphragms and a pressure chamber above the larger diaphragm,said pump comprising means providing suction and vent passages respectively to each side of the actuating diaphragm, a connection between said diaphragms for causing them to move together, a valve actuated by movements of said diaphragms for recurrently connecting opposite sides of said 'actuating diaphragm to suction and vent passages respectively, the actuating diaphragm having the larger effective area so that the forces of atmospheric and subatmospheric pressure exchamber between said diaphragms and a pressure chamber above the larger diaphragm, said pump comprising means providing suction and vent passages respectively to each side of the actuating diaphragm, a connection between said diaphragms for causing them to move together,

a rotary ported valve actuated by movements of said diaphragms for recurrently connecting opposite sides of said actuating diaphragm to suction and vent passages respectively, the actuating diaphragm having the larger effective area so that the forces of atmospheric and subatmos pheric pressure exerted thereagainst overcome such forces imposed on the pumping diaphragm whereby both diaphragms are driven in one direction and then in the opposite direction, and an operative connection between the actuating diaphragm and said valve for abruptly actuating the latter from one position to another substantially upon completion of the movement of the actuating diaphragm in either direction.

' WILLIAM H. LAFFERTY. 

